Johnnys Reloading Bench RL15.5 Vid

[popgun]

I'm sure some of you have watched it. There were a lot of comments theorizing what happened with the 6 ARC load and why the belting. I'm pretty sure to much of the wrong powder was mostly to blame. But a lot of people were wondering about case differences including me since I've gotten a little belting on my Laupa brass. So I hacked a few open.
Left to right Lapua grendel, Starline grendel and Hornady 6 ARC

   

[Bill]

Cool pic, I reckon the hornady brass is wee bit shallowt in the primer pocket too, I have seat primers quite firmly to get em flush

[BluntForceTrauma]

My guess would be the belting has to do with the chamber support at the breech mouth.

[r.tenorio671]

My guess would be the belting has to do with the chamber support at the breech mouth.

....I've thought on this "belting" issue folks have experienced and for some reason I keep wondering if shoulder set back could be a factor.  In my convoluted thinking I "see" a shoulder set back too much allowing gases escaping around the neck to push on the shoulder forcing the casing further back and causing a scenario where there is less case support occuring.   It seems most of the pics folks have posted have shown alot of carbon soot deposited on the neck & shoulder areas.... 

[Dino11]

I read his post on another forum, https://www.snipershide.com/shooting/threads/grendel-like-belted-magnum-problem.7112215/,

And if I understand it correctly he is running the rifle suppressed, that would explain the sooty cases.

He also ran the same load on other brand cases and did not have the belted case. It wasn't until he started loading the Lapua brass with the same load he used with Hornady brass.

I read something awhile back about a Grendel having the same exact issue using Lapua brass, that is were I saw the cut a way cases and the difference between them.

My pet load is almost the exact same load he is using. But your rifle may like something different.
29.4 Lever
105 Nossler RDF
CCI 450 Magnum
Hornady and Starline brass

I have never had a belting problem in 5 different rifles. And I have loaded more grains during load development and for my bolt gun. But I use Hornady brass for the hot loads.

The issue with swipe marks is a characteristic of this caliber, even Hornady factory loads do this, maybe not as bad as he is seeing but non the less it happens. My fix for this was to remove the ejector and radius the sharp edge and round it out to not cut in to the case head. And if I was him I would only use magnum primers if he already does not use them. They are a little bit more durable than standard primers. His primers do not seem to be flattening out but do look like they are flowing into the firing pin hole.

Bottom line is if you are having problems with a certain component you are using, stop using it.

[r.tenorio671]

Dino, mind posting what your CBTO & COAL for your pet load is and the fps attained? Also, are you running it thru a bolt or gasser platform? TIA

[Dino11]

I run them in both bolt and gas gun. I get .5 MOA with both and sometimes better.. These number are for my match grade barrels both of them are a tight chamber, my faxon heavy fluted 20" barrel has a tight chamber as well. Not ordered that way just what I received by chance. Bought it from a forum member right here on this site. it shoots .75 MOA so it's a pretty good barrel.

CBTO is 1.630 and the chamber measures 1.695 in my Odin gas barrel, so the bullet is .065 off the lands. I find that running the bullet .060 to .080 has worked best for me. Chrono numbers for the bolt gun with 30.4g is 2831 for an adverage with an SD of 7.1

The gas gun loaded to 29.4 chrono at 2671 with an SD of 2.1

COAL is 2.295 just barely fits the magazine.

[r.tenorio671]

Thank you, Dino!

When measuring my new, unfired 18" BalAdv barrel I was getting a touch measurement of 1.69692" avg for the RDF's. The first RDF loads I sent down it were seated to a CBTO of 1.679" for an approximate 0.017" jump. These were for the pressure testing of load charges. I only went to 29.1 of LVR as a max and averaged 2672 FPS in new Starline converted brass w/CCI 400's.

I now have 115 pressure test rounds thru the tube so I'll be remeasuring with all of the various bullets I have on hand to see what the "smoothed out" numbers come to. The 2nd round of loads will most likely be with the same max charge used in testing but with varying jumps now to find how much jump the barrel/bullets like. I anticipate a slight increase in fps now that the barrel has been somewhat seasoned, but who knows.

[Dino11]

The shoulder on a fired case with my Odin barrel is 1.188, I bump it back to 1.185. This is a tight chamber, but the jump to the lands is a long .065+ for better accuracy. I know this goes against what most folks are used to but it works for me in 3 match grade barrels. Their is a lot of debate about free bore jump and what works. The latest technology with secant profiled bullets is the long jump works best. bullet profile has come a long ways the past couple years. these long narrow profile bullets require different technology. I have shot out to a mile with 109 long range hybrids and the 115 grain Bergers. the 109's out performed the 115 by a substantial amount at the long distance. I only got a 33% hit with the 115's and a 60% with the 109'S. I still have a bunch of these hard to find bullets, I bought all I could get when I found them in stock.

The folks at the range were amazed that a small bore light load cartridge was making hits at that distance. some of them even said they were going to look into building a rifle to compete as I was hitting the target better than they were with big caliber .338 and Creedmore rounds. The last time to that range the only guy hitting target more than me was a guy shooting 50 BMG.

[popgun]

I originally converted the Lapua brass with about a .0025"- .003" head space and had no soot beyond the neck. Out of 35 rounds I think it was 5 or 6 that didn't feel right when I went to resize and is quite possible there was no visible belt until it went through the die. I'm pretty sure I was using CCI 450 primers loaded 5 rounds of each charge with Lever @ 28.1, 28.4, 28.7, 29.0 and AR-Comp 25.0, 25.3, 25.6. I don't know what load swelled the cases because I didn't notice anything out of the ordinary until I went to resize them. Measurement at the base/head on those were .4395-.440" and may not be a problem if using a die other than Hornady.

[popgun]

It was after this range trip I noticed damage to my bolt. I wonder if it is related?? Hmmm

[r.tenorio671]

FWIW, in my BalAdv barrel the post firing shoulder measurements came out with a low of  1.1932" for the 70VG w/8208xbr to a high of 1.195" for the 105's and 108 w/LVR.  They all started out sized at 1.88" since I didn't have any factory ammo to test with so I went by SAAMI drawing for that initial sizing of the converted Starline 6.5G brass.  All of the loads I tested ended up with a case web measurement of 0.441", matching the SAAMI drawing.  Pre-firing, the case web was sized to 0.438-ish by the Hornady Custom Die sizer, which I believe is basically a SB/FL die.